Bacteria simplifies cellulosic ethanol production

By Lisa Gibson

Bacteria found in sweetgum wood may improve the preprocessing steps for cost-effective production of cellulosic ethanol.

JDR-2, a strain of the wood-decaying bacteria Paenibacillus, can break down and digest hemicelluloses, which in traditional cellulosic ethanol production is broken down by acid hydrolysis. A research team from the University of Florida isolated the strain in 2003, according to James Preston, professor at the university's microbiology and cell science department. The team has mapped out the genome and will work to transfer JDR-2's abilities to bacteria already used for ethanol production through genetic engineering. Preston expects this to be accomplished within the next year. "By engineering the bacteria already being used to produce ethanol to also process hemicelluloses the way this Paenibacillus does, you should be able to significantly simplify the process," Preston said. It's also a possibility that the bacterium can be engineered to make the ethanol itself, he added.

The acid, heating and other traditional preprocessing steps are expensive and require a lot of work. Cellulosic conversion to fermentable sugars is a major roadblock in the cost-effective production of cellulosic ethanol. "Cellulose and hemicelluloses are very difficult to digest to get a complete conversion for maximum yield," Preston said.

Preston came across the bacteria while decaying sweetgum trees to grow shiitake mushrooms on his tree farm in Micanopy, Fla., according to the University of Florida. After studying the unusually uniform composition of the decaying wood, he and his colleagues went on to study the genetics of one of the bacteria digesting it.

"It's not clear if it was indigenous to this tree, although it is a possibility," Preston said, adding that it could be from the soil and can be found in other hard woods, too. "We find it in sawdust from oak and things like that," he said. An article about the bacterium and its abilities was published in the July issue of the journal Applied and Environmental Microbiology.